1. Field of the Invention
The present invention relates to a method of obtaining a composite sealing structure for permanent roadways works and to the corresponding structure.
The sealing of the roadways of permanent works is a special field which employs specific techniques.
It is expedient, in fact, to protect the permanent work against the arrival of water laden with noxious agents. The sealing helps to ensure the correct behavior of the supporting framework; namely by indirectly supports the traffic and its effects
The support, which usually consisting mainly of a concrete roadway, includes pores in the form of residual voids and fissures which store more or less humid air and/or water. This air or this water is released in the form of vapor during the application of the sealing products at temperatures which are always above the ambient temperature, and capable of reaching 250.degree. C. in the case of asphalt. In addition, this water vapor is released during the operating period of the work.
Such release of air or water may produce bubbles, blisters or swellings which might well damage the sealing upon its application, and subsequently, over time, the course of the entire structure including the surface and support.
Up until the present invention, products used for dissipating this air and/or water are, for example, kraft paper or glass web material. These products cannot be applied automatically and to date it has been necessary to lay them manually.
In addition, there is a problem during the application of a bituminous material onto such products; namely, as the finisher passes over, there is the risk of displacing the kraft paper or the glass grating.
In certain techniques of the prior art, the sealing of poured asphalt includes two-grades, the first layer of asphalt mastic being topped by a second sealing and protective layer of gritted poured asphalt.
The sealing based on synthesis materials is ensured by a thin film based on synthetic resin poured into place and adhering to the support.
The sealing with prefabricated sheets is unilayer or two-grade.
All these types of sealing according to the prior art are always placed underneath the road carpet and they constitute the actual sealing of the permanent works.
Besides the problem mentioned above concerning the porosity and the diffusion of the water vapor, one of the major constraints in the production of a sealing for permanent works lies in its turnaround time. The implementation of the sealing is carried out during the final phase of the works and it is often essential to complete it as quickly as possible so as to be able to keep to the delivery dates for the work.
In the prior art, various methods known as Sealing by High-Speed Means or HSM sealing are employed, using mechanical road construction equipment.